Apparatus for generating ultrasonic waves



73-627 I SR 1- Nov. 1, 1966 s. w. o. DKCKINSON 'm 3,282,037

' APPARATUS FOR GENERATING ULTRASONIC WAVES Filed Dec. 19. 1962 IINVENTOR.

i 29 H I 2 7 1B .A v 28' a Ben Wade Ookes Dickinson 111 Y i 3,282,087Patented Nov. 1, 1966 APPARATUS FOR GENERATING ULTRA- SDNIC \VAVES BenWage Oalses Dickinson Ill, 3290 Jackson St San Francisco, Calif. FiledDEC. 19, 1962, Ser. N 245,862

3 Claims. (Cl- 715-715) This invention relates to apparatus forgenerating ultrasonic waves and more particularly to such ap paratus'for use in nondestructive testing or system performance monitoring.

In many applications for ultrasonic waves, it may be desirable toprovide ultrasonic waves which have a relatively high intensity andparticularly intensities which are much greater than those which can beobtained with piezoelectric techniques. There is, therefore, a need fora new and improved method and apparatus for generating ultrasonic waves.

In general, it is an object of the present inventionto provide apparatusfor generating ultrasonic waves which have a high intensity.

Another object of the invention is to provide apparatus of the abovecharacter in which the ultrasonic waves cover a wide frequency spectrum.

Another object of the invention is to provide apparatus of the abovecharacter in which the ultrasonic waves generated are distributedthroughout the wide frequency spectnm.

Another object :f the invention is to provide apparatus of the abovecharacter which is relatively simple.

utilized for creating shock waves or sound waves which impinge upon thewave director 14 to cause ultrasonic wave trains to be produced in thewave director 14. The ultrasonic or high frequency sound waves can bereadily created by the gun T. For example, the explosion of the powderload only will create gun shock waves that will impinge on the wavedirector 14 and thus excite it sonically. The desired high frequencysound waves can be created with greater intensity by adding a solidprojectile or slug that will st ikthe metal Wave director 14 afterfiring the gun, the. c eating an intense wide band impulsive excitationin the metal.

These wide frequency band impulsively generated sound 'waves are createdby the gun T within the wave director 14. For example, with such a gun,a frequency range from less than 1 me. to more than 3.0 me. can bereadily obtained. Also, there is a distribution of the high intensitywave trains throughout this wide frequency spectrum.

The ultrasonic wave trains which areintroduced into the transmit wavedirector 14 are introduced into thecnd or side of the pipe 11 at apredetermined orientation with respect to the longitudinal axis of thetubular body '11. As disclosed. in copcnding application Serial No.

Another object cf the invention is to provide apparatus which because ofthe long time between the initial transmitted pulse (main bang) and thereceivedflaw indication pulse and the lack of a requirement forrepetitive signal-s makes possible the use of impulsively generatedsound covering a wide frequency band.

Additional objects and features of the irivention will appear from thefollowing description in which the pre ferred embodiments are set forthin detail in conjunction with the accompanying drawings.

Referring to the drawings:

FIGURE 1 is an illustration of apparatus incorporating our invention f0.practicing our method.

FIGURE 2A is a schematic view of the presentation on the osm'lloscopewhen the ultrasonic wave train is received after it has reflected from aflaw.

FIGURE 23 is a schematic view of the presentation received on theoxilloscope when a band pass filter is used.

My apparatus for generating ultrasonic waves as used in thenondestructive testing of tubular bodies of members or for systemperformance monitoring is shown in FIGURE 1. In FIGURE 1, there isprovided a tubular member of pipe 11 to be tested. As dcscribed incopending application Serial No. 151,331, filed November 9, 1961, nowPatent No. 3,186,216, the pipe 11 can be provided with adequately smoothends or sides 12 and 13. Transmit and receive offsets or wave directors(sonic COL- pling devices) 14 and 16 are mounted on the ends of the pipe11 as also described in copcnding application Serial No. 15l,33l. filedNo ember 9, 1961, now Patent No. 3,186,216. Alternatively, as disclosedin said copcnding application wave directors can be mounted on the sidewall of the tubular member.

Means is provided for creating wide frequency band impulsively generatedsound-which can take any suitable form as, for example, a powderactuated gun '1 shown in the drawing. This powdcr'actuated gun can be ofany suitable type such as Model No. 238-1 manufactured 151,331, filedNovember 9, 1961, now Patent No. 3,186,216, a substantiallyuncollimatedangularly diverg ing group of helical, ultrasonic wavetrains, all of which are of a single hand or helical path rotationaldirection, represented by the arrows 26 are introduced into the end orside of the pipe and propagate in a direction which is away from thetransmit Wave director 14 and follow helical paths around andlongitudinally within the wall of the pipe toward the other end of thepipe. If it is assumed that a flaw C is present in the pipe, wave trainswill be reflected by the flaw C as indicated by the rays such as 27, 28,and 29, which travel in a direction opposite in hand or helical pathrotational direction to the direction travelled by the transmittedultrasonic wave trains 26.

The reflected wave trains 27, 28, and 29, set up a number of angularlydispersed helices, the number of helical loops between C and the rightend 13 of pipe 11 being determined by the angle with respect to thelongitudinal axis of the pipe 11. At least one of the wave trains 21 isoriented in such a manner that after a partial loop, a complete loop, orseveral complete helical lcops around the pipe, it enters thereceiving'transduoer wave director 16 as shown and is detected by areceive transducer R. In any tubular object, the ultrasonic wave trainsinteract with the pipe wall as described in copcnding application SerialNo. 228,894, filed October 8, 1962. The result is that the tubularobject acts like a mechanical comb I output of the receive transducer Ris connected to a filter 31. The output of the filter is connected to apreamplificr 32 which has a relatively high gain with a broad band pass.The output of the amplifier 32 is connected to 3,136,216. When there isno flaw in the pipe, nothing will be received by the receive transducerR. Therefore, there will be no presentation on the oscilloscope 33.However, when there is a flaw, a presentation will the, presentation isschematically of the type shown in FIGURE 23 on the oscilloscope 33.Thus,'it can be seen that signals which are particularly adapted forflaw indication information can be readily obtained.

Although I have primarily discussed the use of explosives for creatingthe wide frequency band impulsively generated sound because they arerelatively simple and inexpensive to use, it is readily apparent that,if desired, electrical, electromechanicaL hydraulic, and pneumaticdevices can be utilized to createa burst of ultrasound of the widefrequency band within the member to be tested. Thus, it is possible touse a solenoid'actuated device, an

air hammer or anhydraulically operated hammer which will strike a blowand then be removed so that ultrasonic wave, trains are created.Repetitive blows may also be struck with such devices to providerepetitive signals to pulse modulate the shock-excited ultrasonic wavetrains. Alternatively, a pulsed electric arc may be similarly used tocreate a shock wave in a gas such as air which impinges on a wavedirector and in turn results in a burst of ultrasound within the object.These techniques make it possible to transmit information on such wavetrains and also makes it possible to distingui h such wave trains fromultrasonic noise.

Because of the high intensity of the ultrasonic wave trains introduced,the wave trains can be transmitted over relatively great distancesthrough relatively long lengths of tubular members or other objects withrelatively great physical separation between the point of introd *:tionof the wave train and the point of 'recepit of the wave train whilestill obtaining suitable signals at the receive transducer. This highintensity al a makes it possible to use a single pulse for flaw deteconbecause of the positive indication given. Mechanical dixrimination byproper positioning of the receive t a sducer as described in copendingapplication Serial No. 151,331, filed November 9, 1961, now Patentbio-3,185,216, can be used to sense only helical waves and to eliminateor minimize or in other words discriminate against ultrasonic noise(random undirected signals) or other spurious background noise which maybe generated in certain environments such as in drill pipe duringdrilling operations.

Although I have shown the wave trains being intro JOHN P. BEAUCHAMP,new: Examiner.

. 4 4 duced so that they travel in helical paths, it is readily apparentthat such ultrasonic wave trains can be utilized which do not travel inhelical paths in tubular or other geometries such as llat plates asdisclosed in copcnding application Serial No. 228,894, filed October 8,v1962.

It is also apparent from the foregoing that I have provided apparatusfor generating ultrasonic wave trains which is relatively inexpensiveand which is particularly adapted for field use.

I claim: v 1. In apparatus for ultrasonically inspecting a member to betested, said mentberbeing capable of carrying ultra sonic wave trains,at gun adapted to actuate an explosive charge for generating soundenergy having a large component of the same lying in the frequency bandabove one megacycle and of high intensity,

tively connected to said member for coupling said sound energy into themember to be tested and to cause ultrasonic wave trains to be formedwithin the member and to travel through the member.

2. Apparatus as in claim 1 wherein the sound waves are generated by aslug fired from said gun, said slug impinging directly upon said meansoperatively coupling said soundvenergy into the member to be tested.

3. Apparatus as in claim 2 wherein. said means coupling said soundenergy into the member includes a rigid metal element having a surfaceupon which the'slug is adapted to impinge and having an additionalsurface in intimate contact with said member.

I References Cited by the Examiner UNITED STATES PATENTS 2,601,779 7/1952 Firestone 73 67.8" 2,612,772 10/1952 McConnell 73--67.5 2,664,8501/1954 Smith 116-137 2,715,384 8/1955- Meng h; ll6l37 2,804,042 8/1957Gavreau 116-137 2,932,189 4/1960 Carlin 73-617 2,946,217 7/1960 Fruengel73-675 3,066,525 12/1962 Harris 73-67.8 3,121,324 2/1964 Conan 73-6753,166,931 1/1965 Rena-r1 ct a1. 73-618 FOREIGN PATENTS 765,906 1/1957Great Britain.

RICHARD C. QUEISSER, Primary Examiner. f

and means opera-

1. IN APPARATUS FOR ULTRASONICALLY INSPECTING A MEMBER TO BE TESTED,SAID MEMBER BEING CAPABLE OF CARRYING ULTRASONIC WAVE TRAINS, A GUNADAPTED TO ACTUATE AN EXPLOSIVE CHARGE FOR GENERATING SOUND ENERGYHAVING A LARGE COMPONENT OF THE SAME LYING IN THE FREQUENCY BAND ABOVEONE MEGACYCLE AND OF HIGH INTENSITY, AND MEANS OPERATIVELY CONNECTED TOSAID MEMBER FOR COUPLING SAID SOUND ENERGY INTO THE MEMBER TO BE TESTEDAND TO CAUSE ULTRASONIC WAVE TRAINS TO BE FORMED WITHIN THE MEMBER ANDTO TRAVEL THROUGH THE MEMBER.